It is known a process for the manufacture of a metal-rubber nonwoven material with metal wire (USSR Author's Certificate No 183174, Int. Cl. B21F 21/00, published on 1966.01.01), in which a spiral made of cold-hardened wire and extended to get its lead equal to the spiral diameter is used to form a blank of spherical or other shape by winding of the spiral crossed in neighboring layers, and compressed in a mold by unidirectional cold pressing.
The MR material has a wide use in the manufacture of various filters, plain bearings, damped vibration isolators, elastoporous parts. Nevertheless, the pieces made of the MR material by unidirectional pressing present a substantial drawback. The vibration isolators and elastoporous parts are anisotropic and present different elastic and filtering properties in different directions. And what is more, the elastic and filtering properties in the direction of the pressing can differ from said properties in other directions even more than by a factor of 10.
A wire filter is known (patent RU 2470695, Int. Cl. B01D 39/12, published on Dec. 27, 2012), comprising the filtering part made as a body of revolution and consisting of wires wound in spirals laid in rows shifted one relative to each other in the filter axis plane and in the plane perpendicular to the last and submitted to pressing with the possibility to form a multilayer porous structure of the filtering part. Said filtering part is made as a ring with a cylindrical generating element. The wire filter is additionally provided with shells coaxial with the filtering part, embracing each of both ends of the filtering part and made as rings with a cylindrical generating element parallel to the cylindrical generating element of the filtering part ring, and presents a U-shaped section in the plane passing along the rotation axis of the filtering part, open from the side of the filtering part ends and having the possibility for the last to be deepened into the shell rings. The connection of both shells with the filtering part ends deepened into the same along the adjoining cylindrical surfaces is made rigid to form a unique piece and to seal the filtering part ends. Whereupon, the wire used is integrally drawn from one piece with a constant cross-section diameter, or wire fragments are used. The minimum thickness B1 of the filtering part ring is at least 10 times more than the wire diameter d. The length h of the cylindrical generating element of each shell is equal to (0.8−1.0) thickness B of the shell ring wall in a radial direction which is at least equal to the thickness B1 of the filtering part ring. The thickness B of the shell ring wall is equal to (0.01−0.2) of its outer diameter D, and the length of the cylindrical generating element H of the filter is equal to (0.5−5.0) outer diameter D of the shell ring. The diameter d of the wire cross-section is 0.05-1 mm, and the diameter d1 of the spiral is made equal to 1-50 diameters d. The winding lead of spirals for wire fragments is preferably equal to the diameter d of the wire cross-section. Pressing is carried out in the direction of the filter axis with the possibility to form sickle-shaped pores in the porous structure of the filtering part by crossing wires in neighboring rows and by intersecting the spiral axes while laying the wire rows, the average size δ of the filtering part pores, depending on the diameter d of the wire cross-section, is defined by the relationship
      δ    =                  Π        ·        d                    1        -        Π              ,in mm, where Π is the predetermined porosity of the filtering part.
To a certain extent, the present patent relates to processes for the manufacture of filter elements. Pressing in the direction of the filter axis leads to the same drawbacks of the unidirectional pressing of pieces to be made in MR materials, that are analyzed above relative to the USSR Author's Certificate No 183174.
The use of dead-end rings with U-shape section to protect the filtering part ends against damages and to provide sealed joints for the filtration process is an efficient means for the service of the filters, but presents a series of important drawbacks. The lateral surface of the filtering part is reduced, which considerably affects its filtering and other characteristics related to the porous area. Furthermore, the fixation of the rings is not reliable since they are maintained on the filtering part ends only by friction forces. The friction forces values are not stable and decrease during the service life as a result of stress relief in the filtering part material, which can lead, during the filter regeneration, to the separation of the shells with the filtering part.
It is known as well a process for the radial-axial pressing of pieces from materials having disordered structure, in particular, from a wire metal-rubber material (patent RU 2402400, Int. Cl. B21F 45/00, published on Oct. 27, 2010). Such a process considerably eliminates the above mentioned drawbacks of the process for the manufacture of elastoporous parts according to the USSR Author's Certificate No 183174.
Said process comprises the steps of obtaining wire fragments in the form of extended spirals, forming a flat blank from said spiral segments, rolling it, placing the obtained rolled blank into a mold and pressing the blank in several passes. An element of elastic medium is placed into a mold on one side of the blank or on both sides of the same. Pressing of the blank is carried out by its axial compression together with the elements of elastic medium transforming the axial compression into radial pressure on the blank being processed. In this way, the necessary elastic characteristics of the piece to be pressed are provided both in axial and in radial directions, together with the possibility to manufacture a wide variety of parts having continuous and hollow sections.
The above described technical solution is the closest to the solution of the present invention with relation to the combination of essential features and to the technical result obtained.
As drawbacks of the process for the radial-axial pressing of pieces in the MR material according to the patent RU 2402400, one can consider the lack of relationship of technological parameters in the production chain while pressing a blank in several passes. It makes it impossible to achieve the technical result of obtaining new technological procedures implementing the process of the invention. Besides, rolling a flat blank to get assigned dimensions providing for arranging the roll into a mold and for the possibility to place the elastic medium elements is rather difficult to perform due to a low density of the flat blank, which is the reason of instability of the geometrical dimensions of the roll. It brings to the need to get additional operating steps in the blank pressing procedure. For example, the manufacture of a ring from the MR material (see patent RU No 2402400, example) requires three passes of blank pressing with three different elastic elements. These passes lead to the occurrence of a high total spread of geometrical characteristics due to the irregularity of the MR material structure, accumulated in the passes, and, as a consequence, to the decrease of elastoporous elements reliability. The last fact is related to particularities of the elastomer deformation mechanics in the porous space of the MR material. The mentioned factors lead to substantial spread of mechanical characteristics and of reliability for finished products made with the MR material after their calibration with the use of elastic elements. The attempts to reduce such spread are caused by the search of rational forms for the elastic medium, which requires a wide extent of experimental work, of financial and time expenditure.
The object of the present invention is to provide a process for the manufacture of thin-walled elastoporous parts in the form of bushings in the MR material with the selection of the most rational parts for radial and axial pressings of blanks, as well as of their geometrical dimensions for every pressing pass in order to obtain high reliability with predetermined elastoporous characteristics of final products.